Method for (re)selection of control plane and user plane data transmission

ABSTRACT

The invention describes a method for dynamic switching between a control plane data transmission and user plane data transmission avoiding the Detach and consecutive re-attach procedure or TAU procedure. In particular the decision for switch between the different transmission schemes is based on various criteria like the size of the data packet or on total amount of data, etc.

TECHNICAL FIELD

This invention relates to method for (re)selection of control plane anduser plane data transmission.

BACKGROUND ART

The following abbreviations and terminology (whenever differentlystated) are used in the current invention:

TABLE 1 3GPP 3^(rd) Generation Partnership Project AS Access Stratum(use similar to RRC signaling in this invention) DCN Dedicated CoreNetwork NB, eNB Node B, evolved Node B (but can also be any ‘RAN node’implementing 2G, 3G, 4G or future 5G technology) E-UTRAN EvolvedUniversal Terrestrial Radio Access Network (also used as EUTRAN) GGSNGateway GPRS Support Node GPRS General Packet Radio Service HPLMN HomePublic Land Mobile Network HSS Home Subscriber Server IE InformationalElement (used as part of a signalling message) MME Mobility ManagementEntity MNO Mobile Network Operator NAS Non Access Stratum NFV NetworkFunction Virtualization NNSF NAS/Network Node Selection Function PCRFPolicy and Charging Rules Function PGW Packet Data Network Gateway PSMPower Saving Mode RAU Routing Area Update RNC Radio Network ControllerRRC Radio Resource Control PLMN Public Land Mobile Network SGSN ServingGPRS Support Node SGW Serving Gateway TAU Tracking Area Update UE UserEquipment UTRAN UMTS Terrestrial Radio Access Network VPLMN VisitedPublic Land Mobile Network

The following terminologies are used within this invention.

The terms ‘serving node’ or ‘MME/SGSN’ or ‘MSC/SGSN/MME’ or C-SGN (CIoTServing Gateway Node) is generally used through the various embodimentsof this invention to describe a functional entity like MSC, or SGSN orMME, or C-SGN or other possible control plane functional entity in themobile network which terminate the control plane signalling (known asNAS signalling) between the core network and the terminal. The servingnode (MME/SGSN) can be also a functional entity from future generationnetworks which is responsible for mobility and session management.

The term HSS/HLR means the repository where the UE's subscription datais stored and can be either an HSS or an HLR or a combined entity.

The terms ‘terminal’, or ‘device’, or ‘user terminal’ or ‘UE’ (UserEquipment) or ‘MT’ (Mobile Terminal) are used in an inter-exchangeablemanner where all of the terms express the similarly the equipment usedto send/receive data and signalling from network or mobile network orradio access network.

In the recent years due to the penetration of Internet of Things (IoT)and Machine-to-Machine (M2M) technologies the standard bodies like 3rdGeneration Partnership Project (3GPP) start working on improvementsknown as Machine Type Communication (MTC) since Release 10. In order toeven more reduce the price of end devices and the price in theoperator's network for serving such devices, 3GPP carried out a workcalled Cellular IoT (CIoT). This work studied and evaluated thearchitecture enhancement to support ultra-low complexity, powerconstrained, and low data-rate IoT devices. The documentation of thisstudy is captured in the document 3GPPTR23.720. The conclusions were 1)to specify a mandatory control plane (CP) solution, which is documentedin section 2 in the TR and 2) to specify optionally user plane (UP)solution, which is documented in section 18 in the TR. Therefore the CPsolution is also referenced as ‘solution 2’ and the UP solution isreferenced as ‘solution 18’.

The EPS optimized for CIoT supports traffic pattern that is different ascompared to the normal UEs and may support only sub-set and necessaryfunctionalities as compared with the existing EPS. An EPS optimized forCIoT can be enabled by having sub-set of functionalities implemented insingle logical entity C-SGN (CIoT Serving Gateway Node). Mobility andAttach procedures are performed as described in other clauses forcorresponding entities MME, S-GW and P-GW. An example single nodenon-roaming CIoT architecture is shown in FIG. 1. The detaileddescription of the reference points (interfaces) can be found inspecification 3GPP TS23.401 and 3GPP TS23.682.

The selection between CP or UP solution happens during Attach procedureor during a TAU procedures. The UE indicates a ‘Preferred NetworkBehaviour’ including the following:

-   -   Whether Control Plane CIoT EPS optimisation is supported;    -   Whether User Plane CIoT EPS optimisation is supported;    -   Whether Control Plane CIoT EPS optimisation is preferred or        whether User Plane Plane CIoT EPS optimisation is preferred;    -   Whether S1-U data transfer is supported;    -   Whether SMS transfer without Combined Attach is requested;    -   Whether Attach without PDN Connectivity is supported.

The serving node sends in the Attach or TAU accept message the‘Supported Network Behaviour’ information.

In the CIoT EPS optimisations the UE can support “Attach without PDNconnectivity”, which mean that no PDN connectivity, and thus, no EPSbearers are established during the Attach procedure. The UE can requesta PDN connectivity (IP or non-IP) at later point of time using NAS (E)SMsignaling.

If the serving node configures the CP CIoT EPS optimization to be used,the data is transferred between UE and the serving node in NAS PDUsincluding the EPS bearer Identity of the PDN connection they relate to.Both the IP and non-IP data types are supported. This is accomplished byusing the NAS transport capabilities of RRC and S1-AP protocols and thedata transport of GTP-u tunnels between MME and S-GW and between S-GWand P-GW, or if a Non-IP connection is provided by via the MME with theSCEF, then data transfer occurs as indicated in TS 23.682 [74].

FIG. 2 shows a signaling flow of mobile originated (MO) datatransmission for Control Plane CIoT EPS Optimisation (i.e. CP solution).This figure is according to TS23.401. When using CP solution for userdata transport, the MME (for uplink, UL) and UE (for downlink, DL) usesthe EPS Bearer Identity (EBI) contained within the NAS PDUs to identifythe associated EPS bearer.

If the MME wishes to use the CP solution for mobile terminating (MT)services, then an example procedure is shown in FIG. 3 from TS23.401.

In order to depict the different protocols involved in the communicationbetween UE and S/PGW, the protocol stacks over the various interfacesare shown in FIG. 4. Please note that this figure shows the protocolstacks for the CP CIoT Optimisations. One main change introduced by theCIoT EPS optimisations is the support of the GTP-U interface over theS11 interface, i.e. between MME and SGW.

In addition the mandatory agreed CP data transmission, it is alsopossible optionally to use UP data transmission, where the main featureis to the RRC Suspend procedure to store the UE's AS context in the eNB.This procedure is shown in FIG. 5, which is as per TS23.401 section5.3.4A. Additionally in TS23.401 section 5.3.5A a Connection Resumeprocedure is described.

The CIoT EPS optimisations can also apply to LTE (EUTRAN) system. Inparticular, one intention is to cover wide-band (WB) EUTRN UEs (e.g.cat-M) with low cost properties.

However, if a WB EUTRAN UE capable of NB-IoT uses NB-IoT solutions (CPor UP solution), there could be several restrictions when changing RATs.For example, if the UE has activated non-IP connection, then the UE maynot reselect 2G/3G access and continue using the non-IP connection.

The non-IP Data Delivery (NIDD) via SCEF will be capture in 3GPPTS23.682, as currently the 3GPP Tdoc S2-160832 (which needs to beimplemented in TS23.682) shows the procedures. NIDD may be used tohandle mobile originated (MO) and mobile terminated (MT) communicationwith UEs, where the packets used for the communication are not based onthe internet protocol (IP). The configuration of the SCEF for thedelivery of the non-IP data is shown in FIG. 6 description and detaileddescription can be found in 3GPPTdoc S2-160832.

For example purposes, FIG. 7 shows the procedure using which the SCS/ASsends non-IP data to a given user as identified via External Identifieror MSISDN. This procedure assumes that procedures in establishment ofEPS bearer for non-IP data and SCEF configuration procedure (as per FIG.6) are completed.

CITATION LIST Non Patent Literature

[NPL 1]

-   3GPP TS23.401 v144.0, General Packet Radio Service (GPRS)    enhancements for Evolved Universal Terrestrial Radio Access Network    (E-UTRAN) access; Stage 2, v13.5.0, 2015-12.

[NPL 2]

-   3GPP TR23.720, Architecture enhancements for Cellular Internet of    Things; v1.2.0, 2015-11.

[NPL 3]

-   3GPP TS23.203, Policy and charging control architecture; v13.5.1,    2015-09.

SUMMARY OF INVENTION Technical Problem Problem Description

According to the background described above, the selection of the CP andUP solution can happen during Attach procedure or TAU procedure. Thisdescribes the selection of the transmission scheme, but there are nodescriptions how the reselection can be achieved. A reselection oftransmission mechanism can happen for example in case of changing datasize because large data over CP transmission would be inefficient.

The dynamic switching between CP to UP transmission of data is notpossible today. The dynamic selection between CP NB-IoT datatransmission and WB-EUTRAN transmission in case of smartphone supportingCIoT EPS optimizations should be provided as well.

Assuming that reselection between CP and UP data transmission isperformed using Attach procedure, then the problem is that Attachprocedure require explicit signalling and authentication, which canincrease (1) the signalling load in the RAN and CN and (2) the delay forswitching between CP and UP. This may have impact on the userexperience.

The aim of this invention is to provide solution(s) for dynamicswitching between CP and UP transmission by minimizing (1) thesignalling load in the RAN and CN and (2) switching delay. In addition,this invention describes a case where dynamic switching fails.

In case of a smartphone (capable of WB-EUTRAN and CIoT OPtimisations) iscurrently configured with WB-EUTRAN solution, it may be desirable inparticular cases to use data transmission over CP (e.g. in case MT-SMSor MT-NIDD delivery). It is not clear today how to achieve it in anefficient way. Due to some (radio) restrictions, the MME or UE maydecide to apply NB-IoT solution only.

Solution to Problem

In one aspect, the invention provides a core network node, comprising:means configured to transmit data using a Control Plane CIoT EPSOptimization; means configured to determine whether the data istransferred via User Plane or not, based on data size of the data; meansconfigured to transmit a UE context setup request message to a radioaccess network node; means configured to receive a UE context setupcomplete message from the radio access network node when the radioaccess network node sets a radio bearer to a mobile terminal; and meansconfigured to transmit a modify resources request message including aTEID(s) for accepted bearers to a Serving Gateway, S-GW, for PDNconnection between the mobile terminal and PDN Gateway, P-GW.

In one aspect, the invention provides a controlling method forcommunication, comprising: transmitting data using a Control Plane CIoTEPS Optimization; determining whether the data is transferred via UserPlane or not, based on data size of the data; transmitting a UE contextsetup request message to a radio access network node; receiving a UEcontext setup complete message from the radio access network node whenthe radio access network node sets a radio bearer to a mobile terminal;and transmitting a modify resources request message including a TEID(s)for accepted bearers to a Serving Gateway, S-GW, for PDN connectionbetween the mobile terminal and PDN Gateway, P-GW.

In one aspect, the invention provides a radio access network node,comprising: means configured to receive a UE context setup requestmessage includes a User Plane CIoT indication indicating User Plane CIoTEPS Optimization is supported or not from a core network node; meansconfigured to set a radio bearer to a mobile terminal; and meansconfigured to transmit a UE context setup complete message to the corenetwork node.

In one aspect, the invention provides a communication method,comprising: receiving a UE context setup request message includes a UserPlane CIoT indication indicating User Plane CIoT EPS Optimization issupported or not from a core network node; setting a radio bearer to amobile terminal; and transmitting a UE context setup complete message tothe core network node.

Advantageous Effects of Invention

(1) Erroneous handling due to too large PDU size arrival to the EPC maybe avoided or reduced (e.g. solutions 1 and solution 2).

(2) Overload in the limited NB-IoT control plane bandwidth (e.g. in RANnode) may be overcome or alleviated by switching from CP to UPtransmission.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an example single node non-roaming CIoT architecture.

FIG. 2 shows a signaling flow of mobile originated (MO) datatransmission for Control Plane CIoT EPS Optimisation (i.e. CP solution).

FIG. 3 shows signaling flow for MT Data transport in NAS PDUs.

FIG. 4 shows protocol stack between UE and PGW.

FIG. 5 shows eNodeB initiated Connection Suspend procedure.

FIG. 6 shows configuration if SCEF for NIDD procedure.

FIG. 7 shows the procedure using which the SCS/AS sends non-IP data to agiven user as identified via External Identifier or MSISDN.

FIG. 8 shows example signaling flow for statically configured data size.

FIG. 9 shows CP CIoT to UP (CIoT or full LTE) switch when large DL dataarrives and the UE is in idle mode and attached for Control Plane CIoTdata transfer.

FIG. 10 shows Control Plane CIoT to User Plane (CIoT or full LTE) switchwhen large DL Non-IP data arrives and the UE is attached for ControlPlane CIoT data transfer via SCEF.

FIG. 11 shows Signaling flow for MT communication.

FIG. 12 shows a block diagram for UE.

FIG. 13 shows a block diagram for RAN node.

FIG. 14 shows a block diagram for serving node.

DESCRIPTION OF EMBODIMENTS

In order to solve the above described problem, different solutions aredescribed in various example embodiments herewith.

The idea of one solution in the present invention is to allow the MME totake decision about the efficient transmission scheme, i.e. over CP orover UP. The decision in MME may be based (1) on the size of thetransmitted data (or on other data limitation criteria listed below) or(2) on the radio conditions experienced by the UE.

In one solution in this invention (solution 1), the MME informs PGW/SCEFand AS a maximum packet size that EPC or RAN can handle. This is basedon statically configured maximum data size. Once C plane solution ischosen, the MME informs it to PGW/SCEF and AS.

FIG. 8 shows the signaling flow in case of solution 1.

New Parameters:

-   -   The HSS has a subscription data “Treat indicator”. This        parameter indicates an NW behavior when large size of DL packet        arrives to the EPC that exceeds more than maximum size of PDU        that C plane solution can handle. Parameter should have a value        that        -   Discard, or        -   Transfer data as much as possible.    -   The MME sends new parameter “Max. size of PDU” over the GTP-C        message. This parameter is set based on the NAS capability how        large data that NAS can handle PDU. For example, if multiple RRC        handling is not supported, this value should be approximately        1500 bytes. Information of “Max. size of PDU” can be shown as        max size of PDU itself or some bits to indicate “Max. size of        PDU”. For some bits to indicate “Max. size of PDU”, MME/SGW/SCEF        have a common table to show 0:1000 byte, 1:1500 byte etc.    -   The PGW sends new parameter “treat indicator ack”. This        parameter indicates that both “Max. size of PDU” and “Treat        indicator” are comprehended by the PGW and indicates that        whether indicated enforcement is possible or not.

The PGW handles DL PDU packet based on the instruction from the MME.

If a condition matches i.e. DL packet size exceeds a maximum size of PDUthat C plane solution can handle, then enforce it based on an treatindicator. Example, simply discarded DL packet and report it to O&Msystem.

The benefit of solution 1 is that with this approach, unnecessary usertraffic does come to the EPC.

Analogically the MME can inform an SCEF and/or AS in case that non-IPconnection has been established. The SCEF sends new parameter “Max. sizeof PDU” to the AS. The AS sends new parameter “Treat indicator”. Thisparameter indicates an NW behavior when large size of DL or UL packet isarrived to the EPC.

AS behavior: based on the “Max. size of PDU”, the AS does not sends thePDU bigger than the size indicated.

Solution 1 provides the following benefit: erroneous handling due to toolarge PDU size arrival to the EPC can be avoided.

In summary, once a C plane solution is chosen, the MME informs it toPGW/SCEF and AS.

Alternatives:

At least one of following information can be exchanged instead of “Max.size of PDU”.

a) total data volume which UE will receive

b) max throughput or data rate (per certain period (e.g.second/hour/day/week)

c) max number of transmission (per certain period (e.g.second/hour/day/week))

d) a flag to indicate if total data volume which UE will receiveexceeds/lowers a threshold.

Also, two or more parameters among a)-d) can be exchanged together asthe alternative information.

If the apparatuses have implicit “Treat indicator” or if “Treatindicator” is exchanged in other messages, it's not mandatory for CreateSession Request/Response to include “Treat indicator”.

In another solution to the problem (referred as solution 2), the Dynamicreselection of (1) NB-IoT CP or UP solution or (2) NB-IoT solution andWB-EUTRAN solution based on different criteria in the network,preferably in the serving node. For example, one criterion can be due tolarge packet size or large amount of data (e.g. distributed in multipledata segments/packets).

In case large size of packets (IP and non-IP) needs to be handled whenUE is either attached for CIoT over C-Plane or it has C-Plane solutionactivated, then UE/MME transform network configuration to User plane(UP) solution.

The decision for CP or UP selection may be also based on indication fromthe UE about the large data to be sent in the UL. The indication from UEto network can be for example:

-   -   in MO case, the UE can indicate to the MME in e.g. Service        Request procedure or other NAS or RRC signalling message; and    -   in case that the UE is already in CONNECTED or ACTIVE state, and        the UE determines that    -   in MT case, MME sends AS context to eNB for DRB establishment        during transition IDLE->CONNECTED

For example the UE can indicate request for U-plane solution (orWB-EUTRAN) the above described cases.

In MO communication case, if the UE knows that large data is expected tobe sent, then the UE may perform one of the following solutions:

-   -   UE initiates the Detach procedure and re-attaches again. In the        Attach request message, the UE indicates different preferences        for CP and UP based on the expected large data. For example the        UE can indicate UP solution preference in order to transmit the        large data.    -   In order to avoid the increased signaling during the Detach and        Attach procedures, in alternative solution, the UE can initiate        PDN connection release and re-establishment. During the PDN        connection re-establishment, the UE can indicate to the serving        node a) large data is expected, or b) preference for UP        solution.        -   has multiple PDN connections, then UE initiates the UE            requested PDN disconnection procedure for the CIoT            connection and then UE initiates the UE requested PDN            connectivity procedure with U plane solution.

Another aspect of solution 2 is that the MME can decide whether toactivate the UP solution based on the Application identifier (App Id),as some applications may generally send only small data, whereas otherapplications can generally send large amount of data. The applicationcan be detected e.g. via deep packet inspection (DPI) at the networkingress point, e.g. TDF or PGW/PCEF. Later the PGW includes the App Idin the signaling towards SGW and MME, so that MME can decide whether toapply CP or UP transmission for the upcoming data.

In general, solution 2 addresses the use cases where large size of dataneeds to be handled (e.g. in downlink) when a UE is attached to thenetwork and Control Plane solution for CIoT optimization (i.e. transferof data over Control Plane) has been configured. As the data transferover the Control Plane is not efficient or even sometime not possible,it is proposed to dynamically switch from Control Plane CIoToptimization (i.e. transmission over Control Plane, CP) to User PlaneCIoT optimization (i.e. transmission over User Plane, UP) or to full LTEuser plane if the UE is LTE (i.e. WB-UTRAN) capable.

Solution 2.1—Control Plane CIoT to User Plane (CIoT or full LTE) switchfor large non-IP or IP data delivery while the UE is attached and CIoTover Control Plane transmission has been configured. It is assumed thatthe large non-IP or IP data is transmitted over a PDN connectionterminated at a P-GW.

FIG. 9 shows CP CIoT to UP (CIoT or full LTE) switch when large DL dataarrives and the UE is in idle mode and attached for Control Plane CIoTdata transfer.

The steps from FIG. 9 are described in detail as follows:

-   -   1. A CIoT capable UE (LTE UE with CIoT capability or CIoT only        UE) is attached and Control Plane CIoT optimization has been        configured for data transmission.    -   2. Downlink data arrives to P-GW functional entity.        Alternatively if TDF is deployed, the DL data can be processed        at the TDF, so this functional entity.    -   3. The P-GW (or TDF) may perform DPI (Deep Packet Inspection) to        identify the origin of the data (e.g. originating application        identified by ‘app id’). The P-GW forwards the DL packet (s) to        the S-GW. The ‘app ID’ can be included in the GTP-U header of        the DL packet, or alternatively it can be included in the GTP-C        protocol exchange between PGW and SGW.    -   4. The S-GW buffers the DL packet(s) and sends Downlink Data        Notification to the MME including the received data size and the        sender's app id, if available.    -   5. MME inspects the received DDN request for possible decision        whether CP or UP transmission is to be applied. For this purpose        the MME checks the data size to evaluate whether to continue the        DL data delivery over the Control Plane or to switch to one of        the available User Planes (Optimized CIoT User Plane or LTE User        Plane) if the received downlink data is large and it is more        efficient to send it over the User Plane. The MME may also        consider the origin of the DL data (e.g. app id), if available,        in deciding which delivery option, CP or UP, to use.    -   6. MME acknowledges the paging of the UE with DDN ack to the        S-GW.    -   7. If UE in idle mode, the MME pages the UE which causes the UE        to perform Service Request procedure.    -   8. If the MME decides to apply UP data transmission (based on        the DL data evaluation at step 5), the MME sends S I-AP Initial        Context Setup Request message to the RAN Node. This step        activates the data radio bearer(s) (DRBs), The MME can include a        ‘User Plane CIoT’ indication in the Initial Context Setup        Request message to the RAN node in order to explicitly indicate        the setup of UP CIoT use (in case of NB-IoT RAT).    -   9. The RAN Node (e.g. eNB) performs the radio bearer        establishment with the RRC Connection Reconfiguration procedure.        RAN Node may also indicate to the UE its preference for        optimized CIoT User plane in the RRC Connection Reconfiguration        Request message.    -   10. When the data radio bearer(s) are setup, the RAN Node sends        the S1-AP message Initial Context Setup Complete to the MME.

Note: In case the Initial Context Setup procure fails or UE does notrespond to the page to the paging procedure in step 7, then the MMEsends the Downlink Data Notification Failure Indication message to theSGW. The Downlink Data Notification Failure Indication message shallinclude new cause value that indicates the reason of failure. Forexample, data size exceeded limit, switch from Control Plane to UserPlane fails and etc.

-   -   11. The MME sends Modify Bearer Request message to the S-GW        which contains the TEIDs for the accepted EPS bearers and P-GW        confirms with Modify Bearer Response.    -   12. Now the User Plane (CIoT optimized or full LTE) is        established and the DL data can be delivered to the UE over the        establish User Plane.

Solution 2.2—Control Plane CIoT to User Plane CIoT switch for largeNon-IP data delivery while the UE is in idle mode and CIoT optimizationsover Control Plane has been configured.

FIG. 10 shows Control Plane CIoT to User Plane (CIoT or full LTE) switchwhen large DL Non-IP data arrives and the UE is attached for ControlPlane CIoT data transfer via SCEF.

The steps from FIG. 10 are described in detail as follows:

-   -   1. A CIoT capable UE (LTE UE with CIoT capability or CIoT only        UE) is attached for Control Plane CIoT optimization and is in        idle mode.    -   2. Request for non-ip data delivery is received at the SCEF    -   3. The non-ip data request is authorized by the SCEF. The SCEF        checks the size of the non-ip data and submits the non-ip data        size and the non-ip data itself to the MME for delivery to an        UE.

Note: It is possible that the non-ip data size is included in the NIDDDelivery Request from SCS/AS.

-   -   4. MME evaluates the non-ip data size whether it is within the        limits for small data transmission over the Control Plane. If        the received downlink data is large and it is more efficient to        send it over the User Plane, the MME may decide to establish        CIOT optimized User Plane or LTE User Plane, if supported by the        UE.    -   5. If UE in idle mode, the MME pages the UE and the UE comes        back with Service Request.    -   6. The MME sends S1-AP Initial Context Setup Request message to        the RAN Node (e.g. eNB). The MME includes an S1 user plane TEID        that is assigned by the MME so that S1 user plane can be        established between the eNB and the MME. This step activates the        radio bearers and S1 bearers. If the MME decides to deliver the        DL data over the optimized CIoT User Plane (based on the DL data        evaluation at step 5), the MME include the ‘User Plane CIoT’        indication in order to indicate its preference (or request) for        CIoT optimized User Plane type delivery.    -   7. The RAN Node performs the radio bearer establishment with the        RRC Connection Reconfiguration procedure. RAN Node (e.g. eNB)        may also indicate its preference for optimized CIoT User plane        to the UE in the RRC Connection Reconfiguration Request message.    -   8. When the user plane radio bearer(s) are setup, the RAN Node        sends an S1-AP message Initial Context Setup Complete to the        MME. The MME does not send the Modify Bearer Request message to        the S-GW as the S1 user plane is established between the MME and        the eNB. In case the Initial Context Setup procure fails or UE        does not respond to the page to the paging procedure in step 5,        then the MME sends the NIDD Delivery Failure Indication message        to the SCEF. The NIDD Delivery Failure Indication message shall        include new cause value that indicates the reason of failure.        For example, data size exceeded limit, Dynamic switch from        Control Plane to User Plane fails, Unable to page UE, Context        not found, Unable to page UE due to Suspension, UE already        re-attached, Temporarily rejected due to handover/TAU/RAU        procedure in progress, UE not responding, Service denied, UE        already re-attached and etc. If the SCEF receives the NIDD        Delivery Failure Indication message from the MME, then the SCEF        sends the NIDD Delivery Failure Indication message to the SCS/AS        with new cause value in order for the SCS./AS to take an        appropriate action to the Delivery Failure. New cause value can        be for example, data size exceeded limit, Dynamic switch from        Control Plane to User Plane fails, Unable to page UE, Context        not found, Unable to page UE due to Suspension, UE already        re-attached, Temporarily rejected due to handover/TAU/RAU        procedure in progress, UE not responding, Service denied, UE        already re-attached and etc.    -   9. Now the User Plane (CIoT optimized or full LTE) is        established and the DL data can be delivered to the UE.

For the solutions 2.1 and 2.2, at least one of the following alternativeinformation can be exchanged instead of data size (or non-ip data size):

a) max throughput or data rate (per certain period (e.g.second/hour/day/week)

b) max number of transmission (per certain period (e.g.second/hour/day/week))

c) a flag to indicate if total data volume which UE will receiveexceeds/lowers a threshold. Also, two or more parameters among a)-c) canbe exchanged together as the alternative information.

The solutions 2.1 and 2.2 above assume that the UE is in IDLE state whenDL data arrives at the MME. In addition, another solution 2.3 isdescribed below which assumes that the UE is in CONNECTED mode when theDL data arrives at SGW or MME. Specifically, it is assumed that CPtransmission has been configured and applied. The solution proposes tomodify the radio interface configuration (i.e. radio bearers) and S1-Ubearer during the UE is in CONNECTED mode.

The steps from FIG. 11 are described in detail as follows:

-   -   1. While the UE is in CONNECTED state, one of the user plane        nodes (the either the RAN node or the PGW or the SGW) may detect        that the data size or data amount is increasing above a        threshold, or a new application has started data transmission.        Upon such detection, the SGW/PGW or the RAN node inform the MME        about the changed conditions over the user plane (i.e. increased        data, new application, etc.). It is also possible that the MME        detects itself the increased data or new application started        without explicit indication from user plane functional entity.

For example in step 1.1, the SGW (which may have been informed by thePGW, not shown on the figure) informs the MME about new data/PDU size inthe GTP-U header indicating Packet length parameter in the GTP-U header;or SGW uses GTP-C message to inform about new data amount or newapplication (e.g. app id).

Alternatively, in step 1.2, the RAN node can also detect the increaseddata transmission time over the SRB1/SRB2 or control plane (e.g. basedon buffer size above certain threshold). This applicable preferably, butnot limited to, limited control plane transmission bandwidth. Forexample many IoT UEs may receive data simultaneously and the RAN nodetransmission buffer may increase, thus leading to transmission delay.It's possible that eNB indicates such situation to MME, even the dataPDU size is smaller than 1.5 Kbyte and was not detected by SGW/PGW aslarger data. One example of such indication can be “CP load” meaningthat CP transmission channels/bearers are overloaded for one particularor all UE served in a given cell or by given RAN node. Upon suchdetection the RAN node informs the MME about the changed dataconditions.

-   -   2. After receiving the updated information from user plane        (either RAN node or SGW/PGW) or detecting the changed situation        by itself; the MME can determine whether the used CP        transmission should be switched to UP transmission. If the MME        determines that such switch from CP to UP transmission is        needed, the MME initiates a procedure to change the UE's context        in the RAN node, more specifically to initiate e.g. AS security        setup and possible the DRB establishment. For example the S1-AP        Bearer Modification procedure can be used, whereas new        parameters may be included indicating to the RAN node the        activation of DRB(s) and AS security.    -   3. Upon reception of the request from the MME, the Ran node        (e.g. eNB) initiates the AS setup security setup, if not        existing yet, and the establishment of DRB(s). For this purpose        the eNB can use RRC Connection Reconfiguration procedure.    -   4. The UE confirms the RRC connection reconfiguration.    -   5. The RAN node (e.g. eNB) replies to MME about the successful        radio connection modification. For example the eNB can send the        Modify Bearer Response message.    -   6. The MME performs the reconfiguration of the SGW. For this        purpose:

In step 6.1, the MME reconfigures the SGW GTP-U forwarding by updatingthe SGW with the GTP-U TEID of the eNB, e.g. using the Bearer ModifyRequest procedure.

In step 6.2, the MME initiates the release of the existing GTP-U tunnelstate over the S11 interface.

Optionally a new S11 procedure may be specified which performs acombined bearer modification procedure and the GTP-U release procedure.

As a result of the procedures performed as per FIG. 11, the UL and DLdata is transmitted over the user plane (including either NB-IoT UPoptimizations or WB-EUTRAN UP transmission).

With this solution 2.3, large PDU handling is possible while UE canusually stay in CONNECTED state. This results in reduces signalingcompared to e.g. performing of Detach and re-attach procedure.

In additional example embodiment, it is proposed that the UE inCONNECTED mode indicates to the MME about bad radio conditionsexperienced by the UE. For example this can happen when the UE resideson the cell edge (i.e. bad radio conditions, e.g. the UE is inbasement). In such case, in order to save battery power and still toassure reachability, it is proposed that the UE and network (MMS/SGSN)reselect the use of CP transmission from previously used UPtransmission.

For this purpose, the UE can indicate via NAS signaling bad radioconditions to MME/SGSN. In another alternative, the RAN node canindicate the bad radio conditions to the MME/SGSN. The MME/SGSNinitiates radio connection reconfiguration by switching from UP to CPtransmission.

The alternatives of the solution 1 can be applied to the solution 2.

The description below applies to all solutions described in thisinvention.

According to the example embodiments in this invention, the mobileterminal (e.g. a UE) 30 is modified to be able to handle the signalingto/from the network (particularly from the RAN node). The mobileterminal 30 can be described schematically via the block diagram as inFIG. 12:

As shown in FIG. 12, the mobile terminal (UE) 30 comprises a transceivercircuit 31 and a radio interface 32 for transmitting signal to and forreceiving signals from the network (the RAN node). The mobile terminal30 comprises a controller 33 for control of the operation of the mobileterminal 30. The controller 33 is associated with a memory 34.

Software may be pre-installed in the memory 34 and/or may be downloadedvia a communication network or from a removable data storage device(RMD), for example. The controller 33 is configured to control theoverall operation of the mobile terminal 30 by, in this example, programinstructions or software instructions stored in the memory 34. As shown,there software instructions include, among other things, an operatingsystem 35 and a communication control module 36.

The communication control module 36 controls the communication betweenthe mobile terminal 30 and the network. The communication control module36 includes a transceiver control module 37.

According to the example embodiments in this invention, the RAN node(e.g. eNB, NB) 40 is modified to be able to handle the signaling to/fromthe network (to/from MME/SGSN) and to/from the UE 30. The RAN node 40can be described schematically via the block diagram as in FIG. 13.

As shown in FIG. 13, the RAN node 40 comprises a transceiver circuit 41,a network interface 42 for transmitting signals to and for receivingsignals from the serving node, and a radio interface 43 for transmittingsignals to and for receiving signal from the mobile terminal 30. The RANnode 40 comprises a controller 44 to control the operation of he RANnode 40. The controller 44 is associated with a memory 45.

Software may be pre-installed in the memory 45 and/or may be downloadedvia a communication network or from a removable data storage device(RMD), for example. The controller 44 is configured to control theoverall operation of the RAN node 40 by, in this example, programinstructions or software instructions stored in the memory 45. As shown,there software instructions include, among other things, an operatingsystem 46 and a communication control module 47.

The communication control module 47 controls the communication betweenthe RAN node 40 and the mobile terminal 30 and the communication betweenthe RAN node 40 and the serving node. The communication control module47 includes a transceiver control module 48.

According to the example embodiments in this invention, the serving node(MME/SGSN/MSC/C-SGN) 50 should be modified/extended to be able to behaveaccording to the proposed solution(s). Further, modifications to SGW,PGW and HSS are needed. For this purpose the serving node (MME/SGSN) 50,SGW, PGW, SCEF or HSS can be described schematically via the blockdiagram as in FIG. 14:

As shown in FIG. 14, the serving node 50 comprises a transceiver circuit51 and a network interface 52 for transmitting signal to and forreceiving signals from other network entities (the RAN node 40). Theserving node 50 comprises a controller 53 for control of the operationof the serving node 50. The controller 53 is associated with a memory54.

Software may be pre-installed in the memory 54 and/or may be downloadedvia a communication network or from a removable data storage device(RMD), for example. The controller 53 is configured to control theoverall operation of the serving node 50 by, in this example, programinstructions or software instructions stored in the memory 54. As shown,there software instructions include, among other things, an operatingsystem 55 and a communication control module 56.

The communication control module 56 controls the communication betweenthe serving node 50 and the other network entities (the RAN node 40).The communication control module 56 includes a transceiver controlmodule 57.

While the invention has been particularly shown and described withreference to example embodiments thereof, the invention is not limitedthese embodiments. It will be understood by those skill in the art thatvarious changes in form and details may be made therein withoutdeparting from the sprit and scope of the present invention as definedby the claims.

This application is based upon and claims the benefit of priority fromEuropean Patent application No. EP16275027.7, filed on Feb. 17, 2016,the disclosure of which is incorporated herein in its entirety byreference.

1. A core network node, comprising: a memory storing instructions; andat least one processor configured to process the instructions to:transmit first data using a Control Plane Cellular Internet of Things,CIoT, Evolved Packet System, EPS, Optimization; determine whetherfurther data is transferred via User Plane or not, based on data size ofsecond data transmitted after transmission of the first data; transmit aUser Equipment, UE, context setup request message to a radio accessnetwork node based on the determining; receive a UE context setupcomplete message from the radio access network node when the radioaccess network node sets a radio bearer to a mobile terminal; andtransmit a modify resources request message including a Tunnel EndpointIdentifier(s), TEID(s), for accepted bearers to a Serving Gateway, S-GW,for Packet Data Network, PDN, connection between the mobile terminal andPDN Gateway, P-GW.
 2. The core network node according to claim 1,wherein the at least one processor is further configured to determinewhether the further data is transferred via User Plane or not duringdownlink data transfer.
 3. The core network node according to claim 1,wherein the at least one processor is further configured to determinewhether the further data is transferred via User Plane or not duringuplink data transfer.
 4. The core network node according to claim 1,wherein the UE context setup request message includes a User Plane CIoTindication indicating User Plane CIoT EPS Optimization is supported ornot.
 5. The core network node according to claim 1, wherein the UEcontext setup request message is a S1-AP Initial Context Setup Requestmessage, the UE context setup complete message is a S1-AP InitialContext Setup Complete message, and the modify resources request messageis a Modify Bearer Request message.
 6. A controlling method forcommunication, comprising: transmitting first data using a Control PlaneCellular Internet of Things, CIoT, Evolved Packet System, EPS,Optimization; determining whether further data is transferred via UserPlane or not, based on data size of second data transmitted aftertransmission of the first data; transmitting a User Equipment, UE,context setup request message to a radio access network node based onthe determining; receiving a UE context setup complete message from theradio access network node when the radio access network node sets aradio bearer to a mobile terminal; and transmitting a modify resourcesrequest message including a Tunnel Endpoint Identifier(s), TEID(s), foraccepted bearers to a Serving Gateway, S-GW, for Packet Data Network,PDN, connection between the mobile terminal and PDN Gateway, P-GW. 7.The controlling method according to claim 6, wherein the determiningwhether the further data is transferred via User Plane or not isperformed during downlink data transfer.
 8. The controlling methodaccording to claim 6, wherein the determining whether the further datais transferred via User Plane or not is performed during uplink datatransfer.
 9. The controlling method according to claim 6, wherein the UEcontext setup request message includes a User Plane CIoT indicationindicating User Plane CIoT EPS Optimization is supported or not.
 10. Thecontrolling method according to claim 6, wherein the UE context setuprequest message is a S1-AP Initial Context Setup Request message, the UEcontext setup complete message is a S1-AP Initial Context Setup Completemessage, and the modify resources request message is a Modify BearerRequest message.
 11. A radio access network node, comprising: a memorystoring instructions; and at least one processor configured to processthe instructions to: receive a User Equipment, UE, context setup requestmessage includes a User Plane Cellular Internet of Things, CIoT,indication indicating User Plane CIoT Evolved Packet System, EPS,Optimization is supported or not from a core network node; set a radiobearer to a mobile terminal; and transmit a UE context setup completemessage to the core network node.
 12. A communication method,comprising: receiving a User Equipment, UE, context setup requestmessage includes a User Plane Cellular Internet of Things, CIoT,indication indicating User Plane CIoT Evolved Packet System, EPS,Optimization is supported or not from a core network node; setting aradio bearer to a mobile terminal; and transmitting a UE context setupcomplete message to the core network node.
 13. A system comprising thecore network node according to claim 1; and the radio access networknode according to claim
 11. 14. A non-transitory computer readablerecording medium for storing a computer program comprising computerimplementable instructions for causing a programmable communicationsdevice to perform the method of claim
 6. 15. A non-transitory computerreadable recording medium for storing a computer program comprisingcomputer implementable instructions for causing a programmablecommunications device to perform the method of claim 12.